含磺酸根硫醚分子在Au(111)電極上的自組裝行為及其對電化學鍍銅的影響

Cyclic voltammetry (CV) and electrochemical scanning tunneling microscopy (EC-STM) were used to study the self-assembly behavior of 3-(dimethylcarbamothioyl thio) propane-1-sulfonic acid (DPS) on Au(111), as well as its effects on the Cu deposition. The results show that the adsorbed DPS will be oxidized to be an oxidized state (DPSo) at ca. 1.1 V. The adsorbed DPSo self-organizes into ordered structures, (√13 × √31) and (√13 × 6), at 0.8 V when the solution is free of DPS. However, when DPS molecules are contained in the solution, a larger amount of DPS will be oxidized and adsorb on the surface, leading to the formation of aggregate islands. Ordered adlayer cannot be observed in this case. Besides, the adsorbed DPS and DPSo will desorb when the potential is cathodically swept to about 0-0.2 V. The results on the electrochemical Cu deposition reveal that the oxidized DPS can enhance the Cu deposition in both the UPD and OPD stages. Under the observation of an in-situ STM, the UPD Cu film demonstrates as monolayer islands, while the OPD Cu film exhibits a 3-dimentional morphology. When a larger amount of DPSo was formed by prolonging the oxidization time at 1.25 V, the Cu deposition will be enhanced. This study also find that, if the DPS oxidization is performed at the presence of Cu ions, a (DPSo-Cu2+) complex will form. This complex demonstrates a distinct effect to the Cu deposition. In the Cu UPD region, the complex will increase the deposition amount of Cu and, meanwhile, leads to a different arrangement of top-most Cu atoms. In the OPD stage, less Cu islands was deposited. This result is ascribed to the weaker interaction of DPSo-Cu2+ complex to the Cu substrate. Parts of the active sites were occupied by the adsorbed SO42- ions which decreases the deposition rate of Cu.